Voltage references provide a constant output voltage irrespective of changes in input voltage, output current, or temperature. References are needed in such diverse equipment as power supplies, panel meters, calibration standards, data conversion systems, etc.
FIG. 1 illustrates a prior art voltage reference, including an amplifier 120 and a bandgap voltage generator 130. The output of the voltage reference is a stable voltage.
Reference voltage generating circuits are used in integrated circuits. Particularly, in digital mobile apparatuses, in order to reduce the power dissipation, a power saving function is adopted in a reference voltage generating circuit.
Traditionally, Miller compensation has been used for compensating amplifiers used in bandgap implementations. However, this leads to faster gain roll-off due to a single dominant pole and lower power supply rejection. This approach is not adequate for noisy mixed signal environment, where digital spikes on supplies are quite common. In these environments, a fast settling reference with good power supply rejection is needed.